1. Field of the Invention
The present invention relates to an endoscope insertion portion using an actuator unit and a heater unit together for an imaging unit wherein a shape memory member is used in the actuator unit in order to drive a movable optical member of the imaging unit, which is configured to deform according to the temperature and a heating member is used in the heater unit, which is configured to heat a distal end optical member of the imaging unit.
2. Description of the Related Art
In Jpn. Pat. Appln. KOKAI Publication No. 2007-219155, one example of an actuator unit is disclosed. In an endoscope disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2007-219155, an imaging unit is provided at the distal end portion of the endoscope. The imaging unit includes a movable lens frame with a group of objective lenses assembled therein and movable in an optical axial direction. The movable lens frame is configured to be driven by an actuator unit, and a shape memory alloy (which is referred to as SMA, hereinafter) wire is used in the actuator unit.
In Jpn. Pat. Appln. KOKAI Publication No. 11-47080, one example of a heater unit is disclosed. In an endoscope disclosed in Jpn. Pat. Appln. KOKAI Publication No. 11-47080, a heating body is provided so as to enclose the outer periphery of an objective optical system in the distal end portion of the endoscope. Heat produced in the heating body is transmitted to the objective optical system, and the objective optical system rises in the temperature, and therefore, the objective optical system is prevented from being fogged.